Want More Power? Crank Length Matters!

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Will the change to shorter cranks (160mm) on my 61 cm Specialized Tarmac reduce my Cycling Power? I need to use shorter cranks to help manage the osteoarthritis pain in my hips. I already know that shorter cranks are beneficial to opening my hip angle at the top of the pedal stroke, and have no negative impact on my heart rate and exertion with sustained cycling efforts, but what about POWER OUTPUT?!
I set out to record 2 maximum out of the saddle uphill sprint efforts on a local steep climb. It is a 150 m segment with a 19% gradient. My aim was to give a 5 second maximum effort, then hold on for the rest of the segment. I did this first on my Trek Emonda, still with 175 mm cranks, then on my Specialized Tarmac which is now sporting 160 mm cranks.
Even I was amazed at the result!
Contents:
0:00 Intro
2:07 The Climb
3:04 Max Power Test with 175 mm Cranks
4:32 Max Power Test with 160 mm Cranks
5:06 Compare The Results
5:53 Another Marginal Gain?
6:50 More Evidence of More Power!
7:21 Shorter Cranks Benefit Summary
8:08 What Is Next?
8:28 175mm and 160mm Side By Side

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Опубликовано:

15 июл 2024

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Комментарии : 75

@sousuke.higashi 5 месяцев назад

Thank you Podium Physio, I'm 170cm and a natural sprinter. I have tried different size crankarms from 172.5 , 170, 165 and now just started using a 160. From my experience the last 7 weeks on the 165, I can outpace people who needed to go off saddle on a climb, and I don't need to get sport massage every 2000km anymore. I look forward to a more comfortable ride with my 160.

@podiumphysio657 5 месяцев назад

Glad to hear you are more comfortable on the shorter cranks!

@yeyeTF2 5 месяцев назад

2 things: 1) in your 2nd run you hit 88 cadence as your max, up from 84 on your 175. i think you would need to repeat this effort on flat terrain where you are not limited to your easiest gear and griding out, as max power output happens above 105rpm when you are sprinting. this difference in cadence will result in a lower power output for lower cadence as you are limited to the torque you can produce and not leg turnover as well, therefore making this terrain bias in favor towards the shorter cranks 2) peak power output isnt as important for a vast majority of cases in cycling. i would be interested if you compare a 15s, 5min, 15min or something like that where you get a better reflection of the crank arms on your power curve

@podiumphysio657 5 месяцев назад

Hey thanks for your thoughts! I was definitely not in my easiest gear. On trial one I was in the 5th cog and in trial 2 I was in cog 6. I've definitely thought of doing a similar test as a max sprint on the flat. My flat sprint is pretty rubbish though! In a flat sprint at a given cadence (105 RPM or otherwise), the foot speed to turn the shorter cranks will be slower than on the longer cranks, thus the force which the muscles can produce will be higher. I would have thought this would be even more favourable for a flat road sprint? I picked peak power for a bit of fun and I realise there are many other real world scenarios that might interest cyclists more. However once I move away from "Momentary Peak" output and try - say a 15 minute trial, then motivation and other variables come into it. My motivation to go all out on one day might be stronger than my motivation to do the same on a different day... I think for a 5 second burst it is easier to give 100%, twice in a row.

@Edmond347 5 месяцев назад

Great video. I too just had an x-ray of my hips at 51, and was told it was guaranteed I'd need a hip replacement within 10 years. It was devastating to me as cycling is just about the only thing I have in my life that's not disappointing. I started experiencing left hip pain a year ago and it's been progressively weakening my left leg based on the watts and feel. Doesn't help that in 2018 I was put in a coma for 3 days after a car hit me and broke my left tibia on contact, to start with. I've regained full fitness, but my left hamstrings and quads never recovered to the previous size, which is weird. Anyway, I'm 5'9" and rode 172.5 cranks. I just changed to 165 cranks and HOLY SHIT! Much lower lactic acid buildup, and the power balance went the other way, maybe because I was consciously pushing harder with my left leg, which made no difference on 172.5, but does on 165. I'm all in for shorter cranks. I hope your hips feel much better.

@podiumphysio657 5 месяцев назад

Glad to hear the shorter cranks made positive difference to you. I know of 2 riders in their 50's in my cycling group that have had a hip replacement, and both have said they feel great now and are glad they went ahead. I've just chosen to be stubborn and want to put this off for as long as possible. At the moment I feel like I am managing the problem adequately.

@Edmond347 5 месяцев назад

@@podiumphysio657 I think it’s the recovery that would be my main concern. At this age, not being able to ride for months puts you back a lot, I’d think. Btw, what about arthroscopic surgery? I’ve been getting 5 second opinions, haha, and a few good orthopedic surgeons opined that I was a good candidate for an arthroscopic surgery. I understand it can reshape your hip bones, which is what would help my condition. Don’t know how advanced yours is, but just throwing it out there.

@mmfong297 5 месяцев назад

There have been lots of videos out there about this (175cm using 170mm).. but one of the reasons I didn't shorten my crank arm is because of the quick power acceleration I may lose out on. This is not something can be compromised in a criterium race.. unless my body says otherwise. And yes, shorter crank is likely going to provide more comfort, and I can see the benefit of climbing and doing rolling hills. But generally speaking, a bigger/longer arm drives a bigger torque, in order for a shorter/smaller arm to produce the same power, it has to go high rev for higher torque. My assumption to your comparison is that the shorter crankarm allows you have better pedal stroke, such as foot position that activates your muscle group efficiently. This in turn generates more power than your longer cranks

@podiumphysio657 5 месяцев назад

Ive been testing the 15mm shorter cranks for 4 weeks now. So far I've found that: 1 I can produce more power on a steep uphill climb 2 I can produce more power in a high cadence sprint 3 my heart rate is overall lower on a steady state ride between 30 and 50 minutes. I cant specifically comment on how quickly one could accelerate, because I havent tested this, and I'm not sure if my wahoo kicker has the sensitivity to show this type of data. However what I can say is that I waited 6 years from when I first learned about the multiple benefits of shorter cranks to actually trying them for myself. Now that I have them, I see that they are almost universally better for me across multiple criteria, and I wished I'd had the courage to try them sooner. Have a look here for some more info on the background to this testing... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html

@nicklewiscycling 5 месяцев назад

Funny I came across this video as I have been assessing the same thing. Notably when I have run shorter cranks I notice I can't 'accelerate' as well when seated - ie. when in crits or road racing when little surges go that require a sub-maximal 30 - 45 second effort. Though admittedly this is only a 'feeling' and difficult to assess from a data perspective. Every other personal test I did was consistent with your data as well.

@podiumphysio657 5 месяцев назад

Ive only had the shorter cranks for 3 weeks but I've found them just as responsive on the flat. The idea is that if you can self select your gearing, the shorter cranks are just as effective.

@edsinofsky 5 месяцев назад

excellent. I am a believer and have 165s on the way. (Will look for shorter ones too)

@podiumphysio657 5 месяцев назад

Awesome. Love to hear your feedback when you have settled in to the new set up!

@lambo79 5 месяцев назад

Great test! Really useful results. If you could swap the cranks to your other frame, it would be a finite and conclusive test. As there is a possibility the spesh frame is a tad stiffer n has better power transfer

@podiumphysio657 5 месяцев назад

Eventually I will get some shorter cranks for my Emonda, but I dont think they will be the same brand. And I'm not keen on swapping cranks between bikes. I need to recognise the practical limits of these experiments. They are observational, with an attempt to reasonably control obvious variables. The Tarmac may well be stiffer, but I can tell you for sure that it is also 1 kg heavier than the Emonda!

@lambo79 5 месяцев назад

@@podiumphysio657totally understand. Just Glad u shared the results

@canadiandeplorable4512 3 месяца назад

They say that there is a disadvantage for slow MTB trail riding, the standared 175 giving better ballance on the rutted or slow sections. I have recently moved to 165 on the MTB , but to be fair we ride walking paths, easy stuff just for winter training. That said coming from a track back ground, you just adapt because often you need to stall and ballance on the spot as you set up your competitor. So I think its just a relearn. To top it off I have also just built up a new road bike with 165 as well,seems like once again, giving up what I thought was levrage to keep up in the top catagory has only helped overal. When I had moved into the higher catagories I spent months training my spin,as a result of that training I have been able on a bet to hit 163RPM with 175 cranks. Having been down last year with an injury only doing keep up rides on the back of the group, I am seeing my old self this year. As I get fitter I look forward to really seeing my sprint come back using 165 cranks. As a side note,cleat placement is your friend,as long as your calfs can handle the long rides, dont hesitate to try a more forward cleat placement. Happy times. Great vid !

@podiumphysio657 3 месяца назад

Hey there. I'm not a MTB rider so I cant comment on that specifically, but having ridden 160mm cranks almost exclusively for 3 months now, I feel much more comfortable and have seen no reduction in performance. I think it is fairly easy to adapt and more people would enjoy the shorter crank experience if they were prepared to give it a go. Cheers!

@rayF4rio 5 месяцев назад

Another good test would be seated climbing, which would eliminate the element (effect) of the standing power on shorter cranks. I can definitely see where you were much more powerful on the shorter cranks due to not having to raise your knees as far when standing. I think this may affect may be enhanced when standing, and less impactful when seated. Also, very hard to do, but doing 3-5 repeats is the only way to confirm the validity of data. And ensuring conditions and effort are always equal is very hard. But, great info, I've switched from 175's to 170's and love them, but I not sure I have an reason to go shorter at this point, as excessively shorter cranks will then impact seat height and over all fit, requiring lots of follow on changes to dial in the fit again.

@podiumphysio657 5 месяцев назад

Sure, I could do a seated climbing test. I'd need to find a more gentle slope though as I need to get my weight well forward of the rear axel on that steep climb. Easy enough to do. I had planned to do one set of reps with the Emonda first, then the Tarmac second, then reverse order on another occasion either later the same day or another day, but I felt pretty smashed after just doing what you saw. I might consider that in the future though. Yes there are some flow on bike fit considerations when you make a big change to crank length. With contemporary one piece bar and stem set ups it makes life difficult to "tinker"!

@WillPower46 5 месяцев назад

I like your video but before we can take the evidence of your test as a reason to go shorter we really need to see a clear scientific reason as to why the shorter cranks would allow you to produce more power. Perhaps looking at it from a torque vs power scenario where torque is the amount of work being done (turning force on the cranks) so longer should allow you to turn a bigger gear? While power is the rate at which it happens so shorter cranks may allow you to achieve a higher cadence? Any how it is very interesting and I hope you cover the subject in more depth. Thank you.

@podiumphysio657 5 месяцев назад

Have a look at some of the rationale presented here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html

@SnowmEVE 5 месяцев назад

Nice video! Just double checking that you calibrated the power meters to account for the shorter crank length? On the Assioma duo you need to tell the pedals what the crank length is. I assume that's the same for the speed plays.

@podiumphysio657 5 месяцев назад

Sure did!

@tilltheend685 5 месяцев назад

Ive always used 175mm cranks purely that they are comfortable. Im tall and have big legs and just like tge extra lenght. Ive tried shorter cranks of the years but always come back to what is comfortable.

@podiumphysio657 5 месяцев назад

Sure. To each their own. I'm finding the opposite. Shorter cranks are way more comfortable for me and improve my performance.

@musclelessfitness2045 5 месяцев назад

Nicely done. Now it's just a question of endurance. See if you can train for the same weekly KMs (or hours) without experiencing pain in you hips

@podiumphysio657 5 месяцев назад

My Tarmac is my preferred bike as it is newer, has disc brakes, and now has the shorter cranks so most of my riding from now on will be on it. My Emonda will be my spare bike in the future.

@igvabe 5 месяцев назад

thanks for testing. Did you adjust the settings in your powermeter for the shorter cranks?

@podiumphysio657 5 месяцев назад

Yes I did!

@alessandrovigoni 5 месяцев назад

you did also on the Garmin?@@podiumphysio657

@SIvers-or2ke 5 месяцев назад

Mate. Thank you for going to this effort ( pun intended ). I’d be interested in how shorter cranks perform over a longer climb of day 15 mins minimum with and average incline. Wondering if the higher cadence ( expected ) would mean you might run out of steam earlier, compared with longer ( grinding ) cranks. I understand that higher cadence climbing takes a lot of practice and so I’m imagining that it would be a factor for a straight swap like this. Cheers

@podiumphysio657 5 месяцев назад

A few people have made similar comments but the deal is that you self select gearing to match your preferred cadence, which shouldnt change all that much. You work at the same RPM, with mechanical advantages pointed out here... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html The problem with doing a 15 minute outdoor climb is matching efforts between reps. Full gas short efforts are easy to match, they are 100%! On a longer outdoor climb I'd either have to try to match heart rate, which should be fairly consistent (but not identical). See here.... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QKnsjx9WSKQ.html Or try to match power and compare final speed (or heart rate) but then there are may environmental factors that might be confounding variables. Longer indoor tests to mimic longer climbs might be the best option here. Im planning some of these...

@SIvers-or2ke 5 месяцев назад

@@podiumphysio657I see your point and appreciate your reply. However I think I’ve misrepresented my intentions here. I was more interested in how shorter cranks might provide a better climbing platform by allowing a potentially more aggressive seated position for a longer period, thus allowing better breathing etc because you won’t need to stand on the pedals, out of the saddle I’m definitely jumping on the bandwagon with this theory ( at 183cm, using 172.5 crank length ) but am oscillating between your chosen 160 and, the more readily available, 165cm. Again, thank you for posting these clips. It’s not a wasted effort.

@quadfatherclark 5 месяцев назад

@@podiumphysio657 I'd be interested as a 6'2 cyclist, in the longer climbs over 15 minutes in length seated climbing. normally climbing, around or just below ftp. do they help go faster?

@podiumphysio657 5 месяцев назад

@@quadfatherclark Yep that would be interesting but a much harder study to control. I'd have to try to keep my power output at a fixed figure for the whole time and compare speed, but then accounting for all other variables (wind/ temperature/ traffic etc), so the margin for error would be greater due to the difficulty maintaining all of the variables.

@tinyhouseTIAMO 5 месяцев назад

i ha d the same expieriences a few years ago,switching from 172,5 to 150 cranks.my FTP rised from one day to the other from 315 to 330.😀

@musclelessfitness2045 5 месяцев назад

Where did you get 150mm cranks that are hopefully cheaper than 200USD? I could only order 160mm cranks that are not too expensive (still waiting on delivery).

@podiumphysio657 5 месяцев назад

Amazing! Yes I guess that is the sort of test I'm looking at next. A longer steady state ride. 1 hour would be a good mark.

@simonirvine1628 5 месяцев назад

@@musclelessfitness2045 Rotor Aldhu come in a 150mm

@CoffeeTip 5 месяцев назад

Very interesting. Thanks for sharing your findings. I am surprised there isn’t more study done on the effect of crank length. I wonder what the result would be on a rider with a shorter leg length. Would the gain be more, less or would it be a loss?

@podiumphysio657 5 месяцев назад

@@CoffeeTip Not sure. At the moment I'm the only subject in this little study, and I'm 6 foot 4 inches (192cm tall). I'm sure there would be a similar effect in smaller cyclists but maybe to a varying degree.

@StopTheRot Месяц назад

Shorter is definitely better for maximum power. It’s also better for holding a sprint. But, I find longer efforts are better with longer cranks. 20 minute effort on is 347 on 175s and 329 on 170s. Just my experience (with no hip issues). Just a thought - given the difference was large - did you change the crank length on the head unit?

@podiumphysio657 Месяц назад

Yes definitely changed the crank length on my app. I’ve done several comparison videos (175 vs 160 cranks) and nearly every metric in notably improved on shorter cranks for me

@StopTheRot Месяц назад

@@podiumphysio657yup, just watched them. 👍👍

@matthewblue7839 5 месяцев назад

This is interesting, but are strength and power the same thing? The longer cranks would require more strength/power to turn over. But the shorter cranks are easier to turn over, so you hit higher rpm? What were the Rpm data between the two climbs : did you hit higher rpm with the shorter cranks ?

@yeyeTF2 5 месяцев назад

yea this is a good point. he hit a higher cadence using shorter cranks (as expected). given he was going for a 5s max power output, youd expect his cadence to be well over 100. so in this case because he was limited in gearing at 20% gradient, its not exactly the best testing settup. its more of a nod to the idea that shorter crank arms can aid on steep climbs if for some reason you cant or dont want a larger cassette/smaller inner chainring

@podiumphysio657 5 месяцев назад

I'm not a physiologist but i would say strength is the ability to produce force, where power is the ability to produce force as rapidly as possible. Longer cranks require less force to move due to the advantages of leverage. In this test the average RPM with the 175mm cranks was 67, and with the 160mm cranks it was 73. I dont put this down to shorter cranks being easier to turn, I put it down to better mechanical advantage overall with the shorter cranks, and a slightly more favourable cog to chain ring gearing ratio. Here is the thinking on that issue... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html I actually wondered about gearing on the way to the segment, as I am vey familiar with which cog I use with my 11sp Emonda (cog 5 when I am absolutely going for it), but I was not sure which cog to use on the 12 spd Tarmac. My little McGyver test was to roll out 15 full crank circles in gear 5 on the Emonda on the flat, check the distance then redo with the Tarmac in gear 5,6 and even 7. Gear 6 was probably the closest, although still slightly short of gear 5 on the Emonda. The other reason the RPM was faster on the Tarmac is my time up the climb was 3% faster on the Tarmac (29 seconds) vs the Emonda (30 s).

@podiumphysio657 5 месяцев назад

Hey so I've found that the shorter cranks produce better performance on the flat as well. This test was a bit of fun. Its a climb I know well, is pretty intimidating, but suits my slow twitch style well. Some people would stay in the saddle and spin a granny gear but that doesnt work for me.

@Jam789 5 месяцев назад

I also felt similar things, but I only change from 175 to 170. I am planning to try from 175 to 167.5 on another bike

@podiumphysio657 5 месяцев назад

I decided to make a much bigger change (15mm) and am really pleased with the results...

@Jam789 5 месяцев назад

@@podiumphysio657 I am working fine with 170 already. See if any better or worse in the coming 167.5 trial

@stanzapalny2123 5 месяцев назад

Thanks! I subbed. What is your inseam length? I'm 186, but with a high inseam of 92.5 cm and I wonder whether I should go lower than 175 mm.

@podiumphysio657 5 месяцев назад

My inseam is about 91cm. I guess the whole point of this discussion is that the "standard" crank length that the bike companies put on S/M/L/XL bikes are not necessarily best for the cyclist. I just took a jump off the deep end and went to 160mm cranks as they are the shortest I could easily find that matched my groupset. I could have tried 172.5 or 170 or 165 but I wanted to see what a BIG reduction in crank length achieved. All the tests I have done so far are very promising in favour of 160mm

@stanzapalny2123 5 месяцев назад

@@podiumphysio657 I really appreciate the test. I'm just worried about one thing: if my most comfortable cadence is around 97 now to compensate for the shorter crank length I might be forced to increase it beyond the point of being stable on the saddle. I do agree however that 175 mm cranks are a legacy item on our bikes, like the 19-23 mm tires used to be

@podiumphysio657 5 месяцев назад

@@stanzapalny2123 Hey Stan. Yes I use the exact same analogy of tyre width when having these discussions! If you go back and look at the original information I based this test on, by Jim Martin PhD, (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html) he says that if you run shorter cranks, AND you self select your gearing, you can get to a comfortable cadence and foot velocity that will produce more power.

@jamessheard5498 5 месяцев назад

Can you do the same test with swapping the peddles please

@podiumphysio657 5 месяцев назад

Yep great idea. I'll put that on the list of tests to do. Thanks

@zazzleman 4 месяца назад

How timely. 7 years ago a physio recommended 165mm but never did anything. These days the pain is so bad. I have just ordered 165mm

@podiumphysio657 4 месяца назад

Hope it all goes well for you in the transition!

@mikelogan2684 5 месяцев назад

interesting what size chainrings did you use

@podiumphysio657 5 месяцев назад

I'm running a 48/35 chainring combo.

@nzane54 4 месяца назад

Just a thought, but is seems that the shorter crank made you work harder for the same climb???

@podiumphysio657 4 месяца назад

I was working as hard as I could for both efforts. My belief is the shorter cranks are more efficient and effective at translating my leg power to watts on the road

@tonyscott3757 5 месяцев назад

Quick question: Are you absolutely sure you remembered to reconfigure your pedal based power meter to the shorter cranks ? It does not make any sense from a mechanical perspective that shorter cranks increase your max power output (maybe from a biomechanical perspective - that's beyond my expertises). 1092 * 175 / 160 = 1194 which is very close to (read practically identical to) the 1214 max you report with the shorter cranks. If you did reconfigure the power meter then I guess the cause for the increase in max power must be higher cadence with the shorter cranks. If you are right about the increase in power output I really wonder why not everyone in pro cycling are running short cranks...

@sousuke.higashi 5 месяцев назад

Do you know of T. Pogacar? He's on 165mm.

@podiumphysio657 5 месяцев назад

Have a look at this early video I did. There is more to it than purely the lever length... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--3sCebN63rI.html Yes the power meter pedals were configured to the individual crank length. The cadence should be similar to longer cranks because the idea is to select the gear that meets your cadence preference.

@antisha82 5 месяцев назад

Is powermeter the same?

@podiumphysio657 5 месяцев назад

I have Speedplay Powrlink pedals on both bikes, and yes they are calibrated to the crank length in each case

@MrChippiechappie 4 месяца назад

There's nothing wrong with your hips, Try that in the UK riding into 50 kph plus headwind.

@podiumphysio657 4 месяца назад

Yeah I think living in Adelaide, Australia is pretty hard to beat. For cycling and for lifestyle in general.

@simonirvine1628 5 месяцев назад

It may well be far more beneficial to do the test in a static situation due to two facts, number one that you are not only having to deal with the recovery process in the way you were having to deal with it and number two that you were using two different machines. Also you should be doing the test on each crank length at least 10/15 times. Basically it will give you more meaningful results, also it will allow the recovery process to be easier to deal with inside with all the tools at the location to deal with regarding recovery. Ideally you would also use one bike and swap the cranks and pedals over. So you would do 15 takes of each crank length, do the first 7 and give yourself good recovery time then do the other 8 takes and make the recovery time far less and do each crank length on different days. One also needs to replicate the recovery process correctly, basically copied as close as possible. Hope this helps..

@podiumphysio657 5 месяцев назад

Sounds like a big day in the saddle! I'm collating all of these suggestions for future videos. I really appreciate your suggestions and taking the time to discuss improvements with me!

@roiben-ari2375 5 месяцев назад

I didn't hear any mentioning of what power meter is on each bike. A discrepancy between the power meters would be cause a good explanation to why you suddenly gained more than 100 watts in peak power. Especially given the fact that the average speed of both runs was identical

@podiumphysio657 5 месяцев назад

Hey yes I thought the same thing initially. On closer inspection though Strava actually has a 29s moving time for the segment on the 160mm crank effort and a 30s moving time for the 175 mm crank effort. Only 3% different but still different. I dont know how to add the screen shots here to show you... Both bikes have Speedplay Powrlink pedals. A number of people have suggested that I use the same set of power meter pedals across the 2 bikes and repeat the tests, which is fair enough, but I have to say all of the tests I have done on my Wahoo KickR Core, which is independent of the pedals, definitely still support the performance increase of shorter cranks.